#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;

int main()
{
    int n, m;
    cin >> n >> m;
    double ret = 1.0;
    int j = n, k = m;
    while (k--) ret *= j--;
    k = m;
    while (k) ret /= k--;
    for (int i = 0; i < m; i++) ret *= 0.8;
    for (int i = m; i < n; i++) ret *= 0.2;
    printf("%.4lf", ret);
    return 0;
}